public static void main(String ... argv) throws Exception
{
String[] lines = {
"<rdf:RDF",
" xmlns:rdf=\"http://www.w3.org/1999/02/22-rdf-syntax-ns#\";>",
" <rdf:Description rdf:about=\"e\">",
" <p5>verify base works</p5>",
" </rdf:Description>",
"</rdf:RDF>"
};
String eol = System.getProperty("line.separator");
StringBuilder sb = new StringBuilder();
for (String l : lines)
{
sb.append( l ).append(eol);
}
Model model = ModelFactory.createDefaultModel() ;
StringReader sr = new StringReader(sb.toString()) ;
model.read(sr, "http://example/";) ;
model.write(System.out, "N-TRIPLES") ;
System.out.println("-----") ;
model.setNsPrefix("ex", "http://example/";) ;
model.write(System.out, "RDF/XML-ABBREV", "http://another/";) ;
}
The above should create an RDF file that in TTL would be
[ <e> <p5> "verify base works" . ]
I would expect that the read could convert the <e> and <p5> to <
http://example/e> and <http://example/p5> respectively. However,
if you run the code you get
<http://example/e> <p5> "verify base works" .
and then an exception due to a relative URI in the output.
Should the <p5> be converted to <http://example/p5> either by the read or
<http://another/p5> by the write?
Claude
On Tue, Sep 17, 2013 at 10:10 AM, Andy Seaborne <[email protected]> wrote:
> On 17/09/13 07:41, Claude Warren wrote:
>
>> So to summarize:
>>
>> 1) URIs in RDF inside jena are always absolute
>>
>
> "should be" rather than "must be" because there are ways round it but it
> would not be proper RDF.
>
>
> 2) the "base" argument in a read provides the base to make relative URIs
>> absolute.
>>
>
> Yes - except NT where the format does not have a base concept and relative
> URIs are illegal.
>
>
> 3) If the "base" on a read is not provided some reasonable value will be
>> constructed (e.g. file name) so there is no way to create an internal
>> representation of a relative URI through the read() methods.
>>
>
> Yes because there is always a base URI - the current directory.
>
> This is not special to RDF - it comes from the URI RFC 3986, section 5.
>
>
> 4) the "base" argument in a write provides a mechanism to convert absolute
>> URIs to relative URIs in that URIs that have a namespace matching the base
>> are written as relative URIs
>>
>
> Yes (writer and syntax dependent)
>
>
> 5) if the "base" is not provided no conversion to relative URIs will be
>> performed.
>>
>>
> Yes
>
>
>
>> Does that cover it?
>>
>> Claude
>>
>
> Andy
>
--
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LinkedIn: http://www.linkedin.com/in/claudewarren
